<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        const data = {
          arr: [12, 34, 56]
        }
        Object.defineProperty(data, 'arr', {
          get() {
            console.log('getter')
            // Array 可以在数组中收集依赖
          }
        })
    </script>
</body>
</html>